Processionary Caterpillar, the Dangerous Plague of Autumn

In autumn, the processionary caterpillar begins its development stage and prepares for the arrival of winter by building the pockets that will serve as a refuge. But climate change is altering the meteorological process, and with it, the life cycles of many species, which now find favorable conditions to adapt to this seasonal period and become true autumn pests. In autumn and mild winters more proliferation of the processionary caterpillar in spring.

According to experts, the processionary caterpillars – which receive this name for their displacement in a row one after the other, as in the processions – are spreading thanks to the increase in temperatures during autumn and winter, which is causing the modification of phases of its biological cycle and favoring the appearance of pests in unusual periods; and most importantly, altering the phases and techniques of treatments.

The biological cycle of the pine processionary caterpillar is complex. Adult individuals in the form of butterflies mate in summer and do so at night to avoid predatory birds. These butterflies lay their eggs on trees from the end of June until the end of September, so larvae are usually born during October and November. Each laying can count between 100 and 300 eggs, which the female protects by placing scales of her own body. From birth, they begin to feed on the pines, causing the massive fall of the icicles, and generate pockets that serve as protection until the arrival of spring, a season they take to descend.

The caterpillars have a very social and gregarious behavior. During their larval life, they establish cooperative interactions with their setting sisters.

Curiously, they develop their larval life in the same tree and only leave it to look for an adjoining pine if they have exhausted the pine needle where they were born. From the third larval stage, the caterpillars will develop stinging hairs and build dense pockets on the trees in what they spend the winter. In these pockets the days pass and go out to feed at sunset, being tremendously voracious at this time.

At the end of winter and with the arrival of spring, the caterpillars descend to the ground and give life to their characteristic name, forming an Indian row one behind the other. In that way, they protect each other’s heads, which is a food desired by many flying species. After the walk, they roll up to leave no head exposed, always being a female who acts as a guide for the procession. Finally, they are buried in the ground, where they pass to the pupa or chrysalis phase.

The danger of contact with humans and pets

In addition to seriously affecting the pines, the processionary caterpillar -recognizable by its small size, its striking orange color, and its fine stinging hairs- is also a dangerous pest for humans and their pets. The danger of this species lies in its peculiar and curious defensive mechanism. Each caterpillar has a face of 500,000 trichomes or fine hairs, which act as darts or poisoned arrows when they feel threatened. Even without touching them we can receive them because they detach very easily from their body and disperse through the air.

The most common reactions that occur in people are dermatitis, eye injuries, strong allergic reactions, hives, rashes, rashes, and even respiratory problems. In dogs, the most curious pets for their constant sniffing, contact with the processionary can cause damage to the mouth and snout, so severe that they can lead to necrosis in the tissues of the throat and mouth and lead to partial amputations in the tongue. There have also been cases of death in pets due to a severe anaphylactic reaction.

For these reasons, it is recommended to avoid approaching pine forests or areas of the city where you can find plenty of spaces with pine trees, such as swimming pools, parks, and green areas. Doctors recommend, if you have come into contact with them, go quickly to the emergency room to be treated with antihistamines and anti-inflammatories, which will help the reaction caused by the processionary to disappear within days.

Treatments against processionary caterpillar: end therapy

Since the activity of the processionary caterpillar in autumn is concentrated in the pine treetops, it is recommended to pay special attention to any indication of infestation, especially the appearance of pockets, to control and eradicate the pest effectively and always resorting to professional treatments.

In this sense, at Rentokil Initial we have extensive experience in the application of different techniques, products, and treatments to control and eradicate these types of pests effectively. The 4 most used treatments for the processionary caterpillar are:

Application of biocides on the trunk (increasingly obsolete)

Traps with pheromones to capture adult males.

Mechanical devices to capture the caterpillars when lowering the pine.

Endotherapy.

Endotherapy consists of introducing the biocide inside the tree so that it will disperse itself through the vascular system to reach the icicles. With this, it is achieved that when the processionary caterpillar proceeds to feed on them, it will be affected by it by the product.

The endotherapy treatment is done only once and it is advisable to apply it between mid-November and the end of December, dates on which there is a drastic decrease in the rate of pine resin.